The invention relates to a multi-stage refining method for organic bulk materials, according to the fluidized bed principle, for the production of low temperature carbonization gas, liquid products, and if necessary, coke, and an apparatus for performing this method.
A method for the gasification of carbonaceous materials is already known from the DE-OS 2947222, whereby a fluidized bed and fine dust gasification, and if necessary, also a solid bed gasification, take place continuously in a reaction chamber comprising one or several stages. In the direction of the gas stream, a given existing solid bed gasification is followed by two superposed and continuous stages of a fluidized bed gasification, whereby the charge of the crude raw material takes place in the lower stage thereof. Furthermore, in the lower fluidized bed, there are also immersed one or several fine dust gasification chambers having gasification burners mounted on the outside of the reaction chamber.
The method serves exclusively for the recovery of gas, whereby the solid materials are practically completely utilized; the only remaining residue is ash or slag. The configuration of all of the gasification stages in one reaction chamber, however, allows only an insufficient variability of the execution of the method with respect to the production of additional products, as well as to the temperature ratios in the individual stages.
The recovery of liquid products from a gas having compositions which are variable only within narrow limits, therefore is possible only at a high cost. The method further requires high energy consumption, and is unsuitable for the large-scale processing of carbonaceous materials. This deficiency, furthermore, results from the construction of the reactor, which requires high material and technical production expenses.
A method for the production of oil, gas and coke from coal according to the fluidized bed principle is known from the DE-OS No. 2939976. This is a multi-stage method comprising a grinding, a drying, a previous heating, two pyrolysis stages, as well as a stage for the partial gasification and heat development. The overhead streams of individual stages are thereby guided to the fluidization and heating located at upstream stages. The heat for the method is recovered from the partial carbonization of the coal particles in the last stage.
This method allows the regulation of the quantity portions of the end product, however, it does not reveal any possibility for its practical realization, particularly for the large-scale utilization of coal.
A method and an apparatus for the rapid pyrolysis of lignite has already been proposed (WP C No. 10 B/2490798) consisting of a two-stage method according to the fluidized bed principle for the production of coke, gas and tar. The fluidization of the coal is performed in a dryer via an influx floor. The fluidizing medium is produced in a carbonization chamber which is charged in the recycling direction with a part of the vapors from the drying. The dried coal is discharged via a discharge dike and is charged via a conveying apparatus and an intermediary bunker into the pyrolysis reactor. A carbonaceous gas alien to low temperature carbonization is utilized as a fluidizing medium which is heated in a preheater. The fluidized bed, also built up on an influx floor, is furthermore indirectly heated by a heat exchanger, through which is flowing the offgas of an additional carbonization chamber. Subsequently, the offgas heats the preheater, and is utilized as a mixing component for the direct heating in the dryer. The discharge dike provided in both stages simultaneously serves for the regulation of the height of the fluidized bed, and thereby for the determination of the residence time allocated to the coal in each particular stage.
This method still needs improvements with respect to the solid material transport, the determination of the residence time allocated in the stages, and the degree of the energy efficiency. The method, combined with the corresponding equipment, causes energy losses during the solid material transport, and provides an insufficient variability with respect to the quantity portions and the quality of the end product.
The equipment, furthermore, comprises a relatively large amount of apparatus, so that a large-scale utilization of the method requires a high capital investment.